Reduced energy heat pump defrost for unoccupied space

ABSTRACT

Embodiments are directed to determining, by a controller comprising a processor, that a coil associated with a heat pump is subjected to a defrost cycle, determining, by the controller, that at least one of: a conditioned space is occupied, and a thermostat associated with the conditioned space indicates that an energy saving mode is not in use, and enabling, by the controller, an auxiliary heat source based on the determination that the coil is subject to the defrost cycle and the determination that the conditioned space is occupied or the thermostat indicates that the energy saving mode is not in use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 61/760,398, filed Feb. 4, 2013, the entire contentsof which are incorporated herein by reference.

BACKGROUND

A heat pump may be used to generate heat for an indoor space even whenit is relatively cold outside. Typical air source heat pump outdoorcoils will build up frost when operating at some ambient conditions,such as when it is cold outside. The frost may reduce or degrade theperformance of the heat pump. To overcome the performance degradation,the heat pump may be configured to reverse refrigerant direction andtransfer heat from the indoor space to the outdoor coil during a defrostcycle. Operation of the heat pump during the defrost cycle may cause theheat pump to effectively operate as an air conditioner, such that theindoor space or environment is cooled.

It is typical for heat pump controls to call for or engage auxiliaryheat to counteract the cooling effect of the heat pump during thedefrost cycle in order to maintain comfort for occupants in the indoorspace in contact with the conditioned air. Electric resistance heaters,which often serve as the source of the auxiliary heat, are lessdesirable than the heat pump as a source of heat for a variety ofreasons, such as operating cost. By using electric resistance heatersinstead of the heat pump the overall cost to operate a climate controlsystem is increased.

BRIEF SUMMARY

An embodiment of the disclosure is directed to a method comprising:determining, by a controller comprising a processor, that a coilassociated with a heat pump is subjected to a defrost cycle,determining, by the controller, that at least one of: a conditionedspace is occupied, and a thermostat associated with the conditionedspace indicates that an energy saving mode is not in use, and enabling,by the controller, an auxiliary heat source based on the determinationthat the coil is subject to the defrost cycle and the determination thatthe conditioned space is occupied or the thermostat indicates that theenergy saving mode is not in use.

An embodiment is directed to an apparatus comprising: at least oneprocessor, and memory having instructions stored thereon that, whenexecuted by the at least one processor, cause the apparatus to:determine that a coil associated with a heat pump is subjected to adefrost cycle, determine that at least one of: a conditioned space isoccupied based on a detected motion, and an energy saving mode is not inuse in association with the conditioned space, and enable an auxiliaryheat source based on the determination that the coil is subject to thedefrost cycle and the determination that the conditioned space isoccupied or that the energy saving mode is not in use.

An embodiment is directed to a system comprising: a sensor configured toprovide an indication of whether a motion in an amount greater than afirst threshold is detected within a second threshold amount of time,and a processor configured to: determine whether a coil associated witha heat pump is subjected to a defrost cycle, determine whether aconditioned space is occupied based on the indication provided by thesensor, and enable an auxiliary heat source that is located within theconditioned space when the coil is subject to the defrost cycle and whenthe conditioned space is occupied.

Additional embodiments are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example and not limitedin the accompanying figures in which like reference numerals indicatesimilar elements.

FIG. 1 is a schematic block diagram illustrating an exemplary computingsystem in accordance with one or more embodiments of this disclosure;

FIG. 2 illustrates a block diagram of an exemplary environment includinga heat pump in accordance with one or more embodiments of thisdisclosure;

FIG. 3 is a flow chart of an exemplary method in accordance with one ormore embodiments of this disclosure;

FIG. 4 is a wiring diagram in accordance with the prior art; and

FIG. 5 is an exemplary wiring diagram in accordance with one or moreembodiments of this disclosure;

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements inthe following description and in the drawings (the contents of which areincluded in this disclosure by way of reference). It is noted that theseconnections in general and, unless specified otherwise, may be direct orindirect and that this specification is not intended to be limiting inthis respect. In this respect, a coupling between entities may refer toeither a direct or an indirect connection.

Exemplary embodiments of apparatuses, systems, and methods are describedfor defrosting an outdoor coil associated with a heat pump. In someembodiments, a determination may be made whether an indoor space isunoccupied. If the indoor space is unoccupied, then auxiliary heat mightnot be used. If the indoor space is occupied, then auxiliary heat may beused.

Referring to FIG. 1, an exemplary computing system 100 is shown. Thesystem 100 is shown as including a memory 102. The memory 102 may storeexecutable instructions. The executable instructions may be stored ororganized in any manner and at any level of abstraction, such as inconnection with one or more processes, routines, methods, etc. As anexample, at least a portion of the instructions are shown in FIG. 1 asbeing associated with a first program 104 a and a second program 104 b.

The instructions stored in the memory 102 may be executed by one or moreprocessors, such as a processor 106. The processor 106 may be coupled toone or more input/output (I/O) devices 108. In some embodiments, the I/Odevice(s) 108 may include one or more of a keyboard or keypad, atouchscreen or touch panel, a display device, a microphone, a speaker, amouse, a button, a remote control, a joystick, a printer, a sensor, etc.The I/O device(s) 108 may be configured to provide an interface to allowa user to interact with the system 100.

The system 100 is illustrative. In some embodiments, one or more of theentities may be optional. In some embodiments, additional entities notshown may be included. For example, in some embodiments the system 100may be associated with one or more networks. In some embodiments, theentities may be arranged or organized in a manner different from what isshown in FIG. 1.

One or more of the entities shown in FIG. 1 may be associated with oneor more of the devices or entities described herein. For example, one ormore of the entities shown in FIG. 1 may be associated with a heat pumpor a controller as described below.

Turning to FIG. 2, a system environment 200 is shown in accordance withone or more embodiments. The environment 200 may include a structure ora wall 202 that may define or separate an outdoor space 204 and anindoor space 206. The wall 202 may be associated with a building (e.g.,an office building, a residential building, etc.), a room, or the like.

In some embodiments, the environment 200 may be indicative of a singlepackaged system. A single packaged system may be located indoors oroutdoors. Typically, air may be ducted to a single package system fromanother environment. Thus, wall 202 may represent a divider withinequipment to separate a first air stream from a second air stream.

The environment 200 may include a heat pump 210. The heat pump mayinclude a first coil 214 located in the outdoor space 204 and a secondcoil 216 located in the indoor space 206. The coils 214 and 216 may becommunicatively or fluidly coupled to one another 218. For example, thecoils 214 and 216 may be coupled to one another 218 via the use ofrefrigerant, which may be used to facilitate a heat-exchangerelationship.

The heat pump 210 may operate in a number of modes. For example, whenthe heat pump 210 is operating in a first mode, the coil 214 mayfunction as a condenser and the coil 216 may function as an evaporator.Operation in the first mode may be indicative of a cooling or airconditioning mode, such that the indoor space 206 may tend to be cooled.When the heat pump 210 is operating in a second mode, the coil 214 mayfunction as an evaporator and the coil 216 may function as a condenser.Operation in the second mode may be indicative of a heating mode, suchthat the indoor space 206 may tend to be heated.

In some instances, the coil 214 may build up frost, which may degradethe performance of the heat pump 210. The heat pump 210 may be operatedin connection with a “defrost cycle” in order to reduce or eliminate theamount of frost present on the coil 214. The defrost cycle may beindicative of the cooling or air conditioning mode described above.

Cooling the temperature in the indoor space 206 may be undesirable insome instances. For example, if people are occupying the indoor space206 during, e.g., winter, then cooling the indoor space 206 may runcounter to a goal of providing a comfortable indoor climate. Tocounteract or compensate for the cooling effect during a defrost cycle,the heat pump 210 may include, or be coupled to, an auxiliary heatsource 230 that may supply heat to the indoor space 206. The auxiliaryheat source 230 may include electric resistance heaters or strip heatersin some embodiments.

In some embodiments, the heat pump 210 and/or the auxiliary heat source230 may include, or be coupled to, a controller 250. In someembodiments, the controller 250 may include a control board (not shown).The controller 250 may be configured to provide control signals orcommands to the heat pump 210 and the auxiliary heat source 230. Thecontroller 250 may be configured to receive status signals from the heatpump 210 and the auxiliary heat source 230. In some embodiments, thecontroller 250 may include a thermostat 252, which may be a programmablethermostat. In some embodiments, the thermostat 252 may be configured tocommunicate with one or more entities. For example, the thermostat 252may be configured to communicate over one or more networks, such as adata or telephone network. A temperature set point may be received as aninput by the thermostat 252 from a device, e.g., a mobile phone.

As described further below, the controller 250 may be configured todetermine whether a defrost cycle of the heat pump 210/coil 214 shouldbe initiated by turning on or engaging the auxiliary heat source 230. Insome embodiments, such a determination may be based on input provided tothe thermostat 252 or whether the indoor space 206 is occupied.Occupancy may be determined by one or more sensors 254. For example,occupancy may be detected by one or more sensor types, such a motionsensor.

In some embodiments, occupancy may be determined by use of a mobiledevice, such as a mobile phone. For example, a tracking (e.g., a GPStracking) associated with the mobile device may be used to determine alocation or position of the mobile device, and hence, a user associatedwith the mobile device. In some embodiments, occupancy may be determinedwhen the mobile device connects to a network, such as a local network(e.g., Wi-Fi or Bluetooth).

The environment 200 is illustrative. In some embodiments, one or more ofthe entities may be optional. In some embodiments, additional entitiesnot shown may be included. In some embodiments, the entities may bearranged or organized in a manner different from what is shown in FIG.2.

Turning now to FIG. 3, a flow chart of a method 300 is shown. The method300 may be operative in connection with one or more environments,systems, devices, or components, such as those described herein. Themethod 300 may be operative in connection with the system 100 of FIG. 1and/or the environment 200 of FIG. 2. For example, the method 300 may beused to control the temperature of the indoor space 206 during a defrostcycle of the heat pump 210/coil 214.

In block 302, a defrost cycle may be initiated. The defrost cycle may beinitiated based on a number of factors or conditions. For example, insome embodiments when a switch (e.g., a bimetallic switch) associatedwith an outdoor coil (e.g., the coil 214 of FIG. 2) detects a thresholdtemperature, a signal may be provided to a controller (e.g., controller250 of FIG. 2) to indicate that the outdoor coil requests a defrostcycle. The controller may examine timing information or schedulinginformation to determine whether the requested defrost cycle should begranted, and in response to determining that the defrost cycle should begranted, may signal the heat pump (e.g., heat pump 210 of FIG. 2), theoutdoor coil (e.g., coil 214 of FIG. 2), or a circuit associatedtherewith to engage in a defrost cycle. In some embodiments, one or moresensors on the outdoor coil and/or in the outdoor air may be used toinitiate and control the defrost cycle. Other techniques may be used forinitiating a defrost cycle.

In block 304, a determination may be made whether a thermostat (e.g.,the thermostat 252 of FIG. 2) is configured for low energy, unoccupiedspace defrosts. If not (e.g., the ‘no’ path is taken out of block 304),then flow may proceed to block 306 to initiate or perform a defrost onan outdoor coil (e.g., coil 214 of FIG. 2) while turning on auxiliaryheat (e.g., auxiliary heat source 230 of FIG. 2). Otherwise (e.g., the‘yes’ path is taken out of block 304), flow may proceed to block 308.

In block 308, a determination may be made whether a heat pump control(e.g., controller 250 of FIG. 2) includes an occupancy detection sensor(e.g., sensor 254 of FIG. 2). If so (e.g., the ‘yes’ path is taken outof block 308), flow may proceed to block 310. Otherwise (e.g., the ‘no’path is taken out of block 308), flow may proceed to block 312.

In block 310, a determination may be made whether an indoor space (e.g.,indoor space 206 of FIG. 2) is considered unoccupied by sensor logic(e.g., sensor 254 of FIG. 2). For example, the indoor or conditionedspace may be considered unoccupied if motion is not detected by thesensor logic above a threshold amount, optionally as a function of time.The conditioned space may be considered to be occupied when, e.g., amotion in an amount greater than a (first) threshold occurs or isdetected within a (second) threshold amount of time. If the conditionedspace is considered unoccupied by the sensor logic (e.g., the ‘yes’ pathis taken out of block 310), flow may proceed to block 314 to initiate orperform a defrost on the outdoor coil (e.g., coil 214 of FIG. 2) withoutturning on auxiliary heat (e.g., auxiliary heat source 230 of FIG. 2).Otherwise, if the conditioned space is considered occupied by the sensorlogic (e.g., the ‘no’ path is taken out of block 310), flow may proceedto the block 306 to initiate or perform a defrost on the outdoor coil(e.g., coil 214 of FIG. 2) while turning on the auxiliary heat (e.g.,auxiliary heat source 230 of FIG. 2).

In block 312, a determination may be made whether a thermostat (e.g.,thermostat 252 of FIG. 2) has received an input indicating that a heatpump (e.g., heat pump 210 of FIG. 2) and/or an auxiliary heat source(e.g., auxiliary heat source 230 of FIG. 2) should operate in an “energysaving mode.” The “energy saving mode” may be expressed using one ormore terms, such as being “setback,” “away,” “on vacation,” “sleep,”etc. The thermostat may include one or more interfaces (e.g., one ormore keys, buttons, switches, menus, slider bars, voice recognitiondevices, etc.) to facilitate user entry of “energy saving mode” inputs,selections, or parameters.

In some embodiments, the “energy saving mode” may be established orentered into as a function of time or a schedule. For example, at a timeof day when people are not expected to be proximate to the heat pump orauxiliary heat source, the “energy saving mode” may be entered orenabled, and at a time of day when people are expected to be proximateto the heat pump or the auxiliary heat source the “energy saving mode”may be disabled. The schedule may be entered at a thermostat (e.g.,thermostat 252 of FIG. 2).

It is understood that specification of the “energy saving mode”, whichmay indicate that auxiliary heat should be disabled or turned off, couldbe expressed as a counterpart “comfort mode” to indicate when auxiliaryheat should be enabled or turned on. For example, when a “comfort mode”is turned on or enabled, auxiliary heat may be enabled/turned on duringa defrost cycle, and otherwise the auxiliary heat may be disabled.

In some embodiments, specification of the “energy saving mode” may bebased on a setting or a setting with multiple levels. For example,energy saving mode could be implemented as a slider bar between comfortand efficiency. When the slider bar is pushed all the way to “comfort”,auxiliary heat may run with every defrost. When the slider bar is pushedall the way to “efficiency”, auxiliary heat would never run withdefrost. Slider bar settings in between would bring in more modes as youpushed the slider closer to efficiency. Alternately, controls may beestablished to allow a user to select the modes they wanted to disablethe auxiliary heat with on an individual basis.

If the determination of block 312 indicates that the thermostat is in anenergy saving mode (e.g., the ‘yes’ path is taken out of block 312),then flow may proceed to block 314 to initiate or perform a defrost onthe outdoor coil (e.g., coil 214 of FIG. 2) without turning on auxiliaryheat (e.g., auxiliary heat source 230 of FIG. 2). Otherwise, if thedetermination of block 312 indicates that the thermostat is not in anenergy saving mode (e.g., the ‘no’ path is taken out of block 312), flowmay proceed to block 306 to initiate or perform a defrost on the outdoorcoil (e.g., coil 214 of FIG. 2) while turning on auxiliary heat (e.g.,auxiliary heat source 230 of FIG. 2).

In some embodiments, one or more of the blocks or operations (or aportion thereof) of the method 300 may be optional. In some embodiments,the blocks may execute in an order or sequence different from what isshown in FIG. 3. In some embodiments, one or more additional blocks oroperations not shown may be included. For example, if auxiliary heat isturned on or is utilized during a defrost cycle, once the defrost cycleis complete (or at some time thereafter), the auxiliary heat may beturned off.

Turning now to FIG. 4, a wiring diagram 400 in accordance with the priorart is shown. In FIG. 4, a heat pump 402, a fan coil 404, and athermostat 406 are shown. Each of the signals denoted by thealphanumeric characters ‘R’, ‘C’, W2′, ‘Y’, ‘G’, and ‘O’ may be conveyedbetween the heat pump 402, the fan coil 404, and the thermostat 406 on adedicated, separate, or individual wire. Signaling may be performed at aparticular level or value. For example, 24-Volt signaling may be used.The heat stage 2 or ‘W2’ signal may be indicative of a request forauxiliary heat. For example, the heat pump 402 may signal the thermostat406 (via the fan coil 404) that auxiliary heat should be enabled orturned on via the ‘W2’ signal.

Turning now to FIG. 5, a wiring diagram 500 in accordance with one ormore embodiments is shown. In FIG. 5, a heat pump 502, a fan coil 504,and a thermostat 506 are shown. The ‘W2’, ‘W2_(HP)’, and ‘W2_(FC)’signals in FIG. 5 may be associated with the control or enablement ofauxiliary heat. The heat pump 502 may generate a request for auxiliaryheat via the connection ‘W2’-‘W2_(HP)’ between the heat pump 502 and thethermostat 506. The thermostat 506 may include a relay or otherswitching device (not shown) that may conditionally pass or forward therequest for auxiliary heat via the connection ‘W2_(FC)’-‘W2_(HP)’between the thermostat 506 and the fan coil 504. The relay may be openedwhen the premises are unoccupied or when operating in an energy savingmode in order to block the request for auxiliary heat originating fromthe heat pump 502. The relay may otherwise be closed so as to enable therequest for auxiliary heat to be forwarded. Thus, the wiring diagram 500of FIG. 5 provides an ability to selectively forward or block a requestfor auxiliary heat by providing for a wiring change relative to thewiring diagram 400 of FIG. 4.

In some embodiments, a selective forwarding or blocking of a request forauxiliary heat may be performed in software. The use or modification ofsoftware may occur in embodiments where each signal is not allocated orpresent on a dedicated wire. For example, in some embodiments, signals(e.g., control signals or values) may be conveyed using serial ortwo-wire (e.g., clock and data) communications.

As described above, auxiliary heat may be turned on or enabled when anindoor space is considered to be occupied in order to maintain acomfortable temperature during a defrost cycle. The indoor space may beconsidered to be occupied based on a sensory function or parameter(e.g., detected motion), or based on input received at a thermostat orcontroller. When the indoor space is not considered to be occupied, theauxiliary heat may be turned off or disabled during the defrost cycle inorder to conserve or save energy and reduce operating cost. Efficiencymay be improved by avoiding the use of auxiliary heat when the auxiliaryheat does not provide a comfort benefit because a conditioned space(e.g., an indoor space) is unoccupied.

Embodiments of this disclosure may be tied to one or more particularmachines. For example, a controller may be configured to determinewhether an auxiliary heat source should be turned on or enabled during adefrost cycle based on a determination of whether a conditioned space isoccupied or based on a determination of whether an energy saving mode isentered. The controller may include a processor, a thermostat, and/or asensor to provide for such a determination.

Illustrative examples described herein related aspects of thisdisclosure to a thermostat and sensors. The thermostat and sensors maybe used in a variety of applications, such as refrigeration, ovens,heating, ventilation, and air-conditioning (HVAC) appliances (e.g.,furnaces, boilers, heat pumps, air handlers, package units), and ranges.Aspects of the disclosure may be incorporated in controls (e.g.,electronic controls) that run these types of units.

As described herein, in some embodiments various functions or acts maytake place at a given location and/or in connection with the operationof one or more apparatuses, systems, or devices. For example, in someembodiments, a portion of a given function or act may be performed at afirst device or location, and the remainder of the function or act maybe performed at one or more additional devices or locations.

Embodiments may be implemented using one or more technologies. In someembodiments, an apparatus or system may include one or more processors,and memory storing instructions that, when executed by the one or moreprocessors, cause the apparatus or system to perform one or moremethodological acts as described herein. Various mechanical componentsknown to those of skill in the art may be used in some embodiments.

Embodiments may be implemented as one or more apparatuses, systems,and/or methods. In some embodiments, instructions may be stored on oneor more computer-readable media, such as a transitory and/ornon-transitory computer-readable medium. The instructions, whenexecuted, may cause an entity (e.g., an apparatus or system) to performone or more methodological acts as described herein.

Aspects of the disclosure have been described in terms of illustrativeembodiments thereof. Numerous other embodiments, modifications andvariations within the scope and spirit of the appended claims will occurto persons of ordinary skill in the art from a review of thisdisclosure. For example, one of ordinary skill in the art willappreciate that the steps described in conjunction with the illustrativefigures may be performed in other than the recited order, and that oneor more steps illustrated may be optional.

What is claimed is:
 1. A method comprising: determining, by a controllercomprising a processor, that a coil associated with a heat pump issubjected to a defrost cycle; determining, by the controller, that atleast one of: a conditioned space is occupied, and a thermostatassociated with the conditioned space indicates that an energy savingmode is not in use; and enabling, by the controller, an auxiliary heatsource based on the determination that the coil is subject to thedefrost cycle and the determination that the conditioned space isoccupied or the thermostat indicates that the energy saving mode is notin use.
 2. The method of claim 1, wherein an indication that the energysaving mode is in use is expressed as being at least one of: setback,away, on vacation, and sleep.
 3. The method of claim 1, wherein theindication that the energy saving mode is not in use is based on aschedule entered at the thermostat.
 4. The method of claim 1, whereinthe conditioned space is determined to be occupied when a motion in anamount greater than a first threshold is detected by a sensor within asecond threshold amount of time.
 5. The method of claim 1, wherein thecoil is located outside of a building.
 6. The method of claim 1, whereinthe thermostat comprises a device configured to selectively pass arequest for auxiliary heat based on the determination that theconditioned space is occupied or the thermostat indicates that theenergy saving mode is not in use.
 7. The method of claim 6, wherein thethermostat receives the request for auxiliary heat from the heat pump.8. The method of claim 6, wherein the device comprises a relay or aswitching device.
 9. The method of claim 6, wherein the thermostatreceives the request for auxiliary heat in accordance with serialcommunications.
 10. The method of claim 1, further comprising:disabling, by the controller, the auxiliary heat source following thecompletion of the defrost cycle.
 11. An apparatus comprising: at leastone processor; and memory having instructions stored thereon that, whenexecuted by the at least one processor, cause the apparatus to:determine that a coil associated with a heat pump is subjected to adefrost cycle, determine that at least one of: a conditioned space isoccupied, and an energy saving mode is not in use in association withthe conditioned space, and enable an auxiliary heat source based on thedetermination that the coil is subject to the defrost cycle and thedetermination that the conditioned space is occupied or that the energysaving mode is not in use.
 12. The apparatus of claim 11, wherein adetermination that the energy saving mode is not in use is based on atleast one input received at a thermostat.
 13. The apparatus of claim 11,wherein the conditioned space is determined to be occupied when a motionin an amount greater than a first threshold is detected by a sensorwithin a second threshold amount of time.
 14. The apparatus of claim 11,wherein the auxiliary heat source is enabled using a control signal on adedicated wire.
 15. The apparatus of claim 14, wherein the instructions,when executed by the at least one processor, cause the apparatus to:receive a request for auxiliary heat from the heat pump on a seconddedicated wire, wherein the enabling of the auxiliary heat source isbased on the received request.
 16. The apparatus of claim 11, whereinthe auxiliary heat source is enabled based on a control value includedas part of a two-wire serial communication.
 17. A system comprising: asensor configured to provide an indication of whether a motion in anamount greater than a first threshold is detected within a secondthreshold amount of time; and a processor configured to: determinewhether a coil associated with a heat pump is subjected to a defrostcycle, determine whether a conditioned space is occupied based on theindication provided by the sensor, and enable an auxiliary heat sourcethat is located within the conditioned space when the coil is subject tothe defrost cycle and when the conditioned space is occupied.
 18. Thesystem of claim 17, further comprising: a thermostat configured toreceive an input that indicates whether an energy saving mode isentered, wherein the processor is configured to enable the auxiliaryheat source when the coil is subject to the defrost cycle and when theinput indicates that the energy saving mode is not entered.
 19. Thesystem of claim 18, wherein the thermostat is configured to receive theinput via at least one of: a key, a button, a switch, a menu, a sliderbar, and a voice recognition device.
 20. The system of claim 18, whereinthe thermostat is configured to receive the input via a slider bar, andwherein the energy saving mode comprises a plurality of levelscorresponding to positions of the slider bar, and wherein when theslider bar is pushed to a comfort level the auxiliary heat source isenabled with every defrost, and wherein when the slider bar is pushed toan efficiency level the auxiliary heat source is disabled duringdefrost.